1. Field of the Invention
The present invention relates to an apparatus for vitrifying soot preforms from which optical fiber are produced.
2. Related Background Art
Optical fibers or Glass fiber lightguides have been used for a transmission path for optical communication. Optical fiber is fabricated from the preform. As a method of producing preforms from which optical fibers are formed by drawing, the so-called VAD (Vapor Phase Axial Deposition) process and OVD (Outside vapor Phase Deposition) process have been known.
This VAD or OVD process is based on flame hydrolysis. This VAD or OVD process includes the step of sintering soot preforms which are aggregation of glass particles so as to be porous. U.S. Pat. Nos. 5,032,079; 5,114,338; 5,236,482; and 4,969,941 disclose apparatus for sintering the above-mentioned soot preforms.